福建省晋江市城市热岛强度时空变化特征分析     

王可心  陈粲  包云轩  吕青  奴开 《热带气象学报》2019,35(6):852-864

利用传统的气象站法, 结合空间统计学方法(普通克里金插值法), 对福建省晋江市2010—2014年40个自动气象站逐小时温度资料加以计算处理, 分析了晋江市年、季、昼夜热岛强度时空变化规律。(1)晋江市年、季、昼夜热岛强度都呈带状分布, 等值线呈西南-东北走向, 年、季、昼夜变化趋势显著, 北部热岛强度高于南部。五年间热岛强度持续增强, 但增幅不大, 增速放缓。(2)城市化水平的提高, 会导致热岛强度高值出现季节提前, 故旅游区秋冬季热岛强度高于春夏季, 中心城区和产业经济区夏秋季热岛强度高于冬春季。(3)晋江市热岛效应昼夜空间分布格局差异性大, 夜间热岛强度显著高于白天, 最低值出现在14—16时, 中心城区和产业经济区最低值出现时间较旅游区略推迟, 三个功能区的最高值均出现在凌晨。   相似文献   

Element mobility during continental collision: insights from polymineralic metamorphic vein within UHP eclogite in the Dabie orogen     

Y.‐M. SHENG  Y‐F. ZHENG  S‐N. LI  Z. HU 《Journal of Metamorphic Geology》2013,31(2):221-241

Metamorphic dehydration and partial melting are two important processes during continental collision. They have significant bearing on element transport at the slab interface under subduction‐zone P–T conditions. Petrological and geochemical insights into the two processes are provided by a comprehensive study of leucocratic veins in ultrahigh‐pressure (UHP) metamorphic rocks. This is exemplified by this study of a polymineralic vein within phengite‐bearing UHP eclogite in the Dabie orogen. The vein is primarily composed of quartz, kyanite, epidote and phengite, with minor accessory minerals such as garnet, rutile and zircon. Primary multiphase solid inclusions occur in garnet and epidote from the both vein and host eclogite. They are composed of quartz ± K‐feldspar ± plagioclase ± K‐bearing glass and exhibit irregular to negative crystal shapes that are surrounded by weak radial cracks. This suggests their precipitation from solute‐rich metamorphic fluid/melt that involved the reaction of phengite breakdown. Zircon U–Pb dating for the vein gave two groups of concordant ages at 217 ± 2 and 210 ± 2 Ma, indicating two episodes of zircon growth in the Late Triassic. The same minerals from the two rocks give consistent δ¹⁸O and δD values, suggesting that the vein‐forming fluid was directly derived from the host UHP eclogite. The vein is much richer in phengite and epidote than the host eclogite, suggesting that the fluid is associated with remarkable concentration of such water‐soluble elements as LILE and LREE migration. Garnet and rutile in the vein exhibit much higher contents of HREE (2.2–5.7 times) and Nb–Ta (1.8–2.0 times) than those in the eclogite, indicating that these normally water‐insoluble elements became mobile and then were sunken in the vein minerals. Thus, the vein‐forming agent would be primarily composed of the UHP aqueous fluid with minor amounts of the hydrous melt, which may even become a supercritical fluid to have a capacity to transport not only LILE and LREE but also HREE and HFSE at subduction‐zone metamorphic conditions. Taken together, significant amounts of trace elements were transported by the vein‐forming fluid due to the phengite breakdown inside the UHP eclogite during exhumation of the deeply subducted continental crust.  相似文献   

The control of maturity and kerogen type on quantitative analytical pyrolysis data     

Kjell ygard  Steve Larter  Joe Senftle 《Organic Geochemistry》1988,13(4-6)

Quantitative pyrolysis-gas chromatography has been performed on 96 kerogen samples isolated from 17 wells on the Norwegian Continental shelf. Petrographic and bulk geochemical measurements were also performed on the samples, and a combined data set of 117 variables for each sample was analysed using principal components analysis (PCA). This approach provides an objective and reproducible means of kerogen characterisation, which can be easily automated. In addition to objective kerogen characterisation and facile visualisation of facies and maturity related chemical trends, the method has the potential to allow objective prediction of key geochemical parameters such as maturity level from pyrogram data.  相似文献   

An unusual zone of seismic coupling in the Bonin arc: The 1972 Hachijo-Oki earthquakes and related seismicity     

Tetsuji Moriyama  Fumiko Tajima  Tetsuzo Seno 《Pure and Applied Geophysics》1989,129(1-2):233-261

The 1972 February and December Hachijo-Oki earthquakes (M _s=7.3 and 7.4), in the northernmost part of the Izu-Bonin subduction zone, are the only major events (M _s>7.0) in the Bonin arc for the past 80 years. Relocation of the hypocenters, using one smaller event having a wellconstrained focal depth as a master event, shows that the depth of the February event is 10 km shallower than that of the December event. We have determined the rupture process for both events by minimizing the error in waveform between observed and synthetic seismograms. Although the number of available stations are limited, the depth range of the major energy release for the December event extends deeper than for the February one. The rupture propagated up-dip for both events. It is likely that the rupture zone of the two events overlapped, and that the December event ruptured the deeper part. This suggestion is consistent with the observation that the aftershock zones of both events overlap with that of the December event shifted landward. The waveforms of the December event have a smaller high frequency component than those of the February event, suggesting that the stress at the thrust zone became more uniform or reduced after the February event.No thrust type smaller event occurred near the rupture zone. Instead, theP-axes of smaller events are parallel to the dip of the slab and theirT-axes dip to the southwest. Focal depths of these events estimated byP-wave forward modeling are generally between 40–50 km and located beneath the thrust zone. We thus interpret them as the events within the Pacific slab near the zone ruptured by the two major events. The stress concentration around the rupture zone of the major events is suggested to have triggered these slab events. After the occurrence of the large events, the slab events are concentrated near the deeper portion of the rupture zone. These events may have been caused by the loading of the down-dip compressional stress near the down-dip end of the rupture zone due to the rupture. The occurrence of the doublet of large earthquakes and a number of down-dip compressional events beneath their rupture zones in a shallow portion of the subducting slab indicates an unusual zone of seismic coupling in the Bonin arc, most of which is seismically quiescent.  相似文献   

Active tectonics of the Himalaya     

James F Ni 《Journal of Earth System Science》1989,98(1):71-89

The Himalayan mountains are a product of the collision between India and Eurasia which began in the Eocene. In the early stage of continental collision the development of a suture zone between two colliding plates took place. The continued convergence is accommodated along the suture zone and in the back-arc region. Further convergence results in intracrustal megathrust within the leading edge of the advancing Indian plate. In the Himalaya this stage is characterized by the intense uplift of the High Himalaya, the development of the Tibetan Plateau and the breaking-up of the central and eastern Asian continent. Although numerous models for the evolution of the Himalaya have been proposed, the available geological and geophysical data are consistent with an underthrusting model in which the Indian continental lithosphere underthrusts beneath the Himalaya and southern Tibet. Reflection profiles across the entire Himalaya and Tibet are needed to prove the existence of such underthrusting. Geodetic surveys across the High Himalaya are needed to determine the present state of the MCT as well as the rate of uplift and shortening within the Himalaya. Paleoseismicity studies are necessary to resolve the temporal and spatial patterns of major earthquake faulting along the segmented Himalayan mountains.  相似文献   

喜马拉雅山南部的构造复杂性          下载免费PDF全文

秦建业 《地球物理学报》1988,31(4):410-419

根据对恒河盆地西部的多振型宽频带面波频散资料的分析推断,该区的地壳结构不具有大陆地盾的特征,相反,却非常象某些海洋高地。这一异常的海洋型地壳与恒河盆地东部地盾地壳的分界线可能在阿拉瓦利山脉（Aravalli Ridge）。该处地壳的地质特征具有异常高的电导率,其走向垂直于喜马拉雅山脉。目前广为接受的假定认为是构造均匀的印度大陆岩石圈向喜马拉雅山下俯冲。本文的研究结果对此观点提出了置疑:在北部印度大陆内的地壳运动可能存在着差异。我们追溯印度-欧亚大陆的碰撞历史,这个因素恐怕是不容忽视的。  相似文献   

东秦岭寒武纪构造古地理概况   总被引：7，自引：0，他引：7  

杨家騄 《地球科学》1988,(5)

本文提出寒武纪以商丹断裂带为界,东秦岭地区北部属中朝板块南部陆缘区,为主动大陆边缘,以双列岛弧为特征;中部和南部属杨子板块北部陆缘区,由两隆(大陆区北缘和中秦岭微板块)—凹(南秦岭盆地)组成,为被动大陆边缘。  相似文献   

广西弧形构造探讨     

褚有龙 《地球科学》1988,(6)

广西构造实为一弧形构造,它由四个并排的北东—北西向的轭状弧带所组成。每个弧带的前部,为坚硬的岩块所组成,所产生的断裂及岩浆活动对寻找与火成岩有关的矿产有一定意义。每个弧带的后部,产生盆地型沉积,有利于沉积矿产的形成。  相似文献   

怀安蔓菁沟早前寒武纪高压麻粒岩混杂岩带地质特征、岩石学和同位素年代学   总被引：11，自引：19，他引：11  

郭敬辉  翟明国  张毅刚  李永刚  阎月华  张雯华 《岩石学报》1993,(4)

华北克拉通北缘中段怀安蔓菁沟高压麻粒岩混杂岩带产在太古宙怀安杂岩南缘与花岗岩带交界处,由高压基性麻粒岩、辉长质麻粒岩、英云闪长质麻粒岩和少量夕线石榴片麻岩相间排列的席状岩层构成,岩层间被高应变带或剪切带分隔。高压基性麻粒岩是石榴辉石麻粒岩。据石榴石斑晶内包裹的早期矿物(Cpx+Q)估算的早期高压变质作用条件:T=800℃,P>1.4GPa。环绕斑晶的后成合晶反应边矿物组合(P1+Opx+Hb+Cpx)的变质条件为:T=820℃,P为0.7～0.9GPa。全岩Sm-Nd等时线年龄2.65Ga,矿物Sm-Nd等时线年龄1.82Ga,锆石U-Pb一致线年龄1.83Ga。高压基性麻粒岩的原岩代表晚太古代陆壳的最下部,大约在2.7Ga从上地幔分异出来,可能经壳下垫托作用加在早期陆壳底部,随后经历高压变质作用。早元古代晚期,由于地壳规模的大型逆冲作用,使其上升,并经受褶皱形变、剪切推覆和退变质等作用的改造,形成高压麻粒岩混杂岩带。  相似文献   

求解非线性有限元方程的弧长法及在工程稳定分析中的应用   总被引：1，自引：0，他引：1  

刘国明  卓家寿 《岩土力学》1993,14(4):57-67

本文讨论了求解非线性有限元方程弧长法的基本原理及具体实施,并应用于压杆及滑块的稳定性分析。由于弧长法具有确定并通过结构临界应力状态的临界荷载值,因此可以应用于工程稳定性分析。算例表明,弧长法确定的临界荷载值是令人满意的。  相似文献